crash generated by cggetdata (Cogent)

Hello ! I am is some sort of trouble with an application using the cogent library.

cgopen(ResolutionMode, ColorMode, RefreshRate, MonitorMode) generates the following errors according to the MonitorMode

if MonitorMode = 0 (run in a window) ERR gprim:ginit cannot create primary surface (DDERR_NOEXCLUSIVEMODE)

if MonitorMode = 1 (whole screen) or 2 (second display) ERR gprim:ginit cannot set co-operative level 2 (DDERR_EXCLUSIVEMODEALREADYSET)

after this, gpd = cggetdata('GPD'); generates the following error : ERR gprim:gGetData ginit not called

and finally the error that causes the crash ??? One or more output arguments not assigned during call to "cggetdata". Error in ==> define_screen.m gpd = cggetdata('GDP');

The configuration is the following : Matlab v7.12 (R2011a) is running on my laptop at 1366x768 60Hz, and an CRT screen at 1280x1024 75Hz is connected as the second display.

ResolutionMode = 800x600, ColorMode = 0, RefreshRate = 60

This error seems to be generated each time the application runs for the first time on a computer, but until now we were able to ignore it by tweaking the MonitorMode

I am quite new to Matlab, so if not a solution, an explanation on what is happening would be greatly appreciated. Thanks !